1. Field of the Invention
The field of the invention is clock drivers having device presence detection capabilities and methods and systems for detecting a presence of a device.
2. Description of Related Art
In an effort to improve reliability and serviceability of computer systems, computer architects often provide the capability of detecting the presence of a compatible device on a pluggable hardware interface such as, for example, slots for daughter cards on a motherboard or sockets for processor and memory chips. The capability of detecting whether a device is present on a given pluggable interface provides system management software with improved ability to isolate system faults that occur on a pluggable interface. Such an improved ability to isolate system faults allows system management software to more accurately identify correct field replacement units with a high degree of confidence.
Presence detection of devices that plug into a computer system is typically implemented using a dedicated signal pin on the hardware interface into which the device plugs. The dedicated signal pin typically carries a signal to indicate that a device is present whenever a compatible device is inserted into the pluggable hardware interface. When the device is removed from the pluggable hardware interface, the dedicated signal pin typically no longer carries the signal. The dedicated signal pin is typically sampled by circuit logic, such as, for example, an I2C expander input port, which allows system management software to identify whether a device is present.
The current approach of using dedicated signal pins does, however, have certain drawbacks. Dedicated signal pins for presence detection are not always available on every pluggable interface. On those pluggable interfaces for which dedicated signal pins are available, adding dedicated signal pins increases the overall cost of manufacturing the computer system. The overall cost of manufacturing the computer system rises because of the increase in cost to add dedicated signal pins to the pluggable hardware interface connector, to provide extra I2C components in the system to collect device status, and to add complexity to the printed circuit board to wire the signal.